Fluoroalkylthioacetylenes



States trite This invention relates to unsaturated organic compounds.More particularly, it relates to, and has as its chief objects provisionof, certain novel acetylenic compounds and methods for the preparationof the same.

The novel products of this invention are the thioacetylcues of theformula RfSCECR, wherein R is a polyfluoroalkyl group, i.e., an alkylgroup having more than one fluorine substituent, of up to 10 carbons andR is hydrogen, a monovalent hydrocarbon radical of up to 10 carbons, R 8or R;. More specifically, the monovalent hydrocarbon radical can bealkyl, aryl, cycloalkyl, aralkyl, or alkaryl.

The polyfluoroalkylthioacetylenes of this invention can be prepared byreaction of a polyfiuoroalkanesulfenyl halide, e.g., apolyfluoroalkanesulfenyl chloride, with an alkali metal or halomagnesiumacetylide. The alkali metal and halomagnesium acetylides have theformula XCECY, wherein X is hydrogen, a monovalent hydrocarbon radicalof up to 10 carbons, a polyfluoroalkyl radical of up to 10 carbons or Y.As in the definition of R, given above, monova-lent hydrocarbon radicalsinclude alkyl, cycloalkyl, aryl, aralkyl, and alkaryl radicals. Y inthis formula is an alkali metal, i.e., lithium, sodium, potassium,rubidium, or cesium, or ahalomagnesium group, the halogen of which hasan atomic number of at least 17, i.e., -MgCl, MgBr, or MgI. The reactionof the polyfluoroalkanesulfenyl halide with the alkali metal orhalomagnesium acetylide is conveniently carried out by first preparing asolution of the alkali metal or halomagnesium acetylide in an ether asreaction medium, e.g., in diethyl ether, di-n-butyl ether, or dioxane,by conventional methods. For example, a diethyl ether solution ofphenylethynylmagnesium bromide can be prepared by reaction ofphenylacetylene with an ether solution of ethylmagnesium bromide (whichin turn has been prepared by conventional methods). There is then addedto the ether solution of the alkali metal or halomagnesium acetylide atleast one mole of a polyfluoroalkanesulfenyl halide, e.g.,trifluoromethanesulfenyl chloride, for each atom of alkali metal or eachhalomagnesium group in the acetylide being employed, and the reactionmixture is maintained at a temperature between and +50 C., preferablybetween 0 and C. for a few hours to obtain complete reaction. Usually1-2 hours are suflicient, but reaction times of up to several days canbe employed. The reaction mixture is then poured into a stirred mixtureof ice and water, optionally containing a mineral acid, e.g.,hydrochloric acid, to remove the alkali metal halide or magnesium halideby-product that is present. The organic layer is separated and combinedwith ether extractions of the aqueous layer, and then fractionallydistilled after drying over a desiccant, such as anhydrous magnesiumsulfate.

An alternative method for the preparation of some of thepolyfluoroalkylthioacetylenes of this invention involves the reaction inthe presence of ultraviolet light of a halogen of atomic number between17 and 35, inclusive, i.e., chlorine or bromine, with al,2-bis(polyfluoroalkylthio)ethane of the formula R SCI-I CH SR whereinR, is a polyfluoroalkyl group of up to 10 carbons, to form atent adihalo-1,2-bis(polyfluoroalkylthio)ethane which is then icedehydrohalogenated by treatment with an alkali metal hydroxide.

This alternative process is conveniently carried out by treating a1,2-bis(polyfluoroalkylthio)ethane in which the polyfluoroalkyl groupscontain not more than 10 carbon atoms each with at least two moles ofchlorine or bromine for each mole of the fluoroalkylthioethane at atemperature between 0 and C. in the presence of ultraviolet light. Theuse of a solvent or reaction medium in this process is not necessary,but, if desired, an inert solvent for the reactants can be used.Examples of suitable solvents include carbon tetrachloride, chloroform,and ethylene dichloride. It is very convenient to carry out thehalogenation at the temperature at which the reaction mixtures refluxes.

Any convenient source of ultraviolet light can be employed. For example,sunlight, or commercial mercury arc sunlamps are suitable. Anyirradiating device that generates light containing some radiation ofultraviolet or near-ultraviolet wavelengths, i.e., light of wavelengthsbetween about 0.015 and 0.04 micron, can be used. The rate of reactionwill of course depend on the intensity of the ultraviolet radiationsreaching the reaction mixture and this will of course depend on thestrength of the ultraviolet light source and its distance from thereaction vessel. Reaction times of several hours to several days arenormally employed.

This halogenation reaction usually results in the formation of somemonohalogenated products as well as a mixture of the various isomericdihalogenated products. The monohalogenated products can be separatedfrom the dihalogenated products by fractional distillation. It is notnecessary to isolate the individual dihalogenated isomers since they allreact with alkali metal hydroxide in the next step of the process togive the desired bis(polyfluoroalkylthio) acetylenes.

The dehydrohalogenation step of this process is conveniently carried outby contacting a dihalo-l,2-bis-(polyfluoroalkylthio)ethane obtained asdescribed above with at least 2 moles of an alkali metal hydroxide,e.g., potassium hydroxide. A wide range of operating temperatures can beused in this process. Temperatures ranging between 40 C. and 200 C. arequite suitable. The dehydroh'alogenation takes place rapidly at thesetemperatures. The use of an inert reaction medium is not essential inthis process, since molten alkali metal hydroxide at a temperature ofabout C. can be used. However, it is convenient to employ an inertmedium. Dispersions of powdered alkali metal hydroxides in high boilinghydrocarbons are useful in this process. Thepolyfluoroalkylthioacetylenes obtained in the reaction should not,however, be exposed to the alkali metal hydroxide for especially longtimes as such exposure causes decomposition of the products. A stream ofinert gas, e.g., nitrogen, passed through the reaction zone is aconvenient way of removing the polyfluoroalkylthioacetylene from thereaction zone when an alkali metal hydroxide is used in the absence ofany reaction medium. The polyfiuoroalkylthioacetylene produced in thereaction can be isolated from the reaction mixture by conventionalmethods, e.g,, by fractional distillation.

Polyfiuoroalkanesulfenyl halides used as starting materials in theprocess of this invention can be prepared by known methods. For example,trifluoromethanesulfenyl chloride can be made by reaction oftrifiuoromethyl disulfide with chlorine as described by Haszeldine andKidd in J. Chem. Soc. 1953, 3219. The alkali metal and halornagnesiumacetylides can be prepared by reaction of the appropriate acetylene withan alkali metalalkyl or aryl, or alkylmagnesium halide by well knownmethods. The 1,2-bis(polyfluoroalkylthio)ethanes used as startingmaterials in the alternative process can be made by the photocatalyzedreaction of a vinyl polyfluoroalkyl sulfide with a polyfluoroalkanethiolas described in coassigned U.S. application Serial No. 58,910, filedSeptember 28, 1960.

The products and process of this invention are illustrated in furtherdetail by the following examples in which the proportions of ingredientsare expressed in parts by weight unless otherwise specified.

EXAMPLE I Phenyl T rifluoromethylthio)Acetylene Ethylmagnesiurn bromideis prepared in conventional manner (Organic Syntheses, vol. 36, p. 87)from 4.78 parts of magnesium and 16.7 parts of ethyl bromide in 36 partsof anhydrous diethyl ether. Twenty parts of phenylacetylene (0.196 mole)in 21 parts of anhydrous diethyl ether is added to the solution of theGrignard reagent and the mixture is refluxed for 0.5 hour. While thetemperature of the mixture is maintained at 15-20 C. by externalcooling, 26.6 parts of trifluoromethanesulfenyl chloride (0.195 mole) isadded by means of a gas inlet tube, about 1 hour being required for thisaddition. The mixture is then poured into a stirred icewater-hydrochloric acid mixture. The product is removed by twoextractions with 100 ml. portions of diethyl ether. The combined ethersolution is washed twice with water, dried over anhydrous magnesiumsulfate and distilled through a small Vigreux still. There is obtained7.23 parts (24% of theory) of crude phenyl(trifluoromethylthio)acetyleneboiling at 27- 31 C./0.05 mm. and having a refractive index, n of1.5373. This product is combined with a similar fraction obtained by themethod of Example II and redistilled through a small spinning bandstill. A fraction distilling at 32 C./0.40 mm., n =1.5213, is analyzed.

AnaIysis.-Calcd for C H F S: F, 28.2%; S, 15.8%. Found: F, 27.2%; S,15.7%.

EXAMPLE II Plzenyl( Trifluoromethylthio)Acetylene To approximately 30parts of a diethyl ether solution of phenyltithium containing 4.12 partsof phenyllithium at C. is added 5 parts of phenylacetylene dropwise.After the addition is completed (about 30 minutes being required), themixture is stirred at 10 C. for 0.5 hour. To this reaction mixture,there is then added 10 parts of trifluoromethanesulfenyl chloride over aperiod of one hour. After being stirred for an additional hour, thereaction mixture is flooded with Water. Thirty-six parts of diethylether is added to the reaction mixture and the ether layer is separated,Washed twice with water, and dried over anhydrous magnesium sulfate.Upon distillation of this ether solution through a small Vigreux stillthere is obtained 1.5 parts of crude phenyl(trifluoromethylthio)acetylene distilling at 3245 C./0.65 mm. and having a refractive index,11 of 1.5373.

EXAMPLE III Bis( T rifluorometlzylthi0)Acetylene CFaSCECSCFa CFaSCCH An-butyl ether solution of a Grignard reagent is prepared by placing 36.5parts of magnesium in 1000 parts of n-butyl ether and adding 163.5 partsof ethyl bromide with stirring. Acetylene, purified by bubbling throughconcentrated sulfuric acid and dried by passing through a soda-limetower, is passed into this Grignard solution for 6 hours atapproximately room temperature (25. 0.). Some heat is evolved during thereaction and a fine precipitate is formed. Then, while continuing thestirring, 204 parts (1.5 mole) of trifluoromethanesulfenyl chloride isgradually passed into the reaction mixture at room temperature minutesbeing required). The reaction mixture is cooled by a water bath to keepthe temperature at 25 C. A trap cooled to 80 C. is attached to thereaction vessel to collect any unreacted trifluoromethanesulfenylchloride, but only a trace is collected. After standing two days at roomtemperature the reaction mixture is filtered and distilled quickly, afraction distilling at 30- C. being collected. Redistillation of thisfraction gives 13.0 parts (B.P. 30 35 C. mostly 32 C.) which is found byvapor phase chromatography to be a mixture oftrifluoromethylthioacetylene and bis(trifluoromethyl)disul fide. Nuclearmagnetic resonance spectroscopy (both F and H) indicates the presence oftrifluoromethylthioacetylene in a cut purified by preparative scale gaschromatography. Another fraction, B.P. 79-82 C., amounting to 11.22parts and having a refractive index, of 1.4102 containsbis(trifluoromethylthio)acetylene.

EXAMPLE IV Bis(Trifluoromelhylthi )Acetylene bu omsorncmsorwm,CF3SCH2CHBISCF3 CFBSCHCHSUF: KOH I l CFsSCECSCFa Br Br d anCFaSCBrrCHrSCFs A mixture of 60 parts of 1,2-bis(trifluoromethylthio)ethane, 106 parts of bromine and 240 parts of carbon tetrachloride isheated to reflux in a glass reaction vessel and irradiated with acommercial sunlamp for a period of 3 days. Upon distillation of thereaction mixture through a spinning band still there is obtained 35.3parts (44% of theory) of 1bromo-1,2-bis(trifiuoromethylthio)ethanedistilling at 75 C./77 mm., n =1.4226, and 43 parts (43% of theory) ofdibromo-1,2-bis(trifluoromethylthio) ethane distilling at 59 C./7 mm., n=l.4599.

Analysis.-Calcd for C H BrF S Br, 25.8%; F, 26.9%. Found: Br, 25.9%; F,26.7%.

Analysis.Calcd for C H Br F S Br, 41.2%; F, 29.4%. Found: Br, 41.9%; F,29.4%.

An examination of the fluorine and proton nuclear magnetic resonancepatterns of the dibromo fraction indicates the presence of two compoundsin comparable amounts. Thus, both possible dibromo compounds, viz.,l,2-dibromo-1,2-bis(trifluoromethylthio)ethane and 1,1-dibromo-1,2-bis(tritluoromethylthio)ethane are formed during the brominationreaction.

Fifty parts of potassium hydroxide (minimum assay 85%) is heated in areaction flask surrounded by an oil bath and fitted with a droppingfunnel, a gas inlet tube, and an exit tube which leads to a trap cooledwith a mixture of solid carbon dioxide and acetone. A slow stream ofnitrogen is passed through the gas inlet tube and the oil bath is heatedto about C. At this temperature the potassium hydroxide becomes liquidand during a period of 0.5 hour 10 parts ofdibromo-1,2-bis(trifluoromethylthio)ethane (prepared as described in theprevious paragraph) is added dropwise. At the end of the addition, thematerial in the cold trap is distilled and there is obtained 3.06 parts(52% of theory) of bis(trifluoromethylthio) acetylene distilling at 8486C., n =1.3930-1.3935.

Analysis.-Calcd for C F S F, 50.3%; S, 28.4%. Found: F, 50.4%; S, 28.4%.

The fluorine nuclear magnetic resonance pattern obtained on thiscompound consists of a single resonance at 1288 c.p.s. (relative to thefluorine resonance of trifiuoroacetic acid). The infrared absorptionspectrum obtained on this product is quite simple, containing strongabsorption in the 8-9 micron region (C-F) and a peak at 13.2 microns (S.CF

6 .Analysis.-'-Calcd for'C H ClF S: c, 49.4%; H, 2.3%; F, 17.4%. Found:C, 49.5%; H, 2.4%; F, 16.7%.

' The examples have illustrated the products and process of thisinvention by. specificreference to. certain polyh, CzFsSCHzCHzSOFs-I-BrzCQFASCHCH2SCF3 5 fluoroalkyltlnoacetylenes. However, this invention m-3. cludes any polyfluoroalkylthioacetylene of the formula 2 sSCHzCHSCFaR $CECR, wherein R; and R have the meanings defined r hereinbefore.Examples of other products of this inven- CZFEISCECHSCFS' 5 tion includethe, compounds listed in the third column v 1 of the following Table I.The specific polyfiuoroalkyl- CJBSCECSCFS c p scgg H scF and sulfenylhalides and alkali metal or halomagnesium acet- CQFESCHWBHSCM ylidesused in preparing these are listed in the first two The 'bromination of14.9 parts of l-trifluoromethylthiocolumns of the table.

TABLE I Reactants Polyfluoroalkylthioacetylene CFaSBr CHsCECMgICHsCEOSCFs n-CzFrSCl nC4HnCECMgBr C4HoCECSCaF1 /CHz-CH2 CH:CH2(CFzkCFSCl CH1 CHOECK... C CHCECSOF(OFS)I GHQ-CH2 CFs(CF2)sSClCsH5OH2CECS(CF2)aCFa CF3(CFz)sSCl-- CHaCeH=CS(CF2)s a CF$(CF2)11SCLFa(CF2)u E 2)n F: HCFClCFzSCL C2H5CE C2H5CEOSCF2CHFC1 HOFzCFzSCl HECMgCl HCEOSCFQCHFQ /CH2 /CH2 HCFzCHFSCl CHCECCS CH1 OHCECSCHFCHFE C 2 7CH2 ClCFgCFzSCl CFgCECMgBr CFaCECSCFzCFzCl ClCFzCHgSCl CzHsCECMgBICzH5CECSCH2OFzCl 2-pentafiuoroethylthioethane by the procedure describedin Example IV for the bromination of 1,2-bis(trifiuoromethylthio)ethaneleads to the formation of a monobromo fraction (B.P. 5459 C./25 mm., n=1.4013) and 6.75 parts ofdibromo-1-trifluoromethylthio-2-pentafluoroethylthioethane boiling at82-85 C./25 mm., n =1.4373. This dibromo fraction is believed to be amixture of the three possible isomers (illustrated by above equation).

EXAMPLE VI Phenyl Ch lorodifluoromethylthio)Acetylene A solution ofphenylethynylmagnesium bromide is prepared as described in Example I andto this solution, cooled in an ice water bath, is added 31 parts ofchlorodifluoromethanesulfenyl chloride during one hour. The mixture ispoured into a large excess of ice water and the crude product is removedby two extractions with 71 parts of ether. After being dried overanhydrous magnesium sulfate, the ether solution is distilled through asmall Vigreux still. There is obtained 12.4 parts of crude productdistilling at 44 C./0.25 mm. to 74 C./0.57 mm. Redistillation of thismaterial through a small spinning band still yields 4.9 parts ofphenyl(chlorodifiuoromethylthio)acetylene distilling at 49 C./ 0.50 mm.to 51 C./0.60 mm., n =1.5587.

The fluoroalkylthioacetylenes of this invention are useful for variouspurposes. Thus they are useful as solvents for polymers. Such solutionsmay be used for applying the polymer to wood, paper, etc. For example,samples of paper are waterproofed by immersion in a 10% solution ofvinyl trifluoromethyl sulfide polymer inbis(trifluoromethylthio)acetylene at reflux followed by air drying. In asimilar manner samples of wood and paper are waterproofed by immersionin a 10% solution of low molecular weight tetrafiuoroethylene polymer(M.P. 83- 145) in bis(trifiuoromethylthio)acetylene at reflux followedby air drying. Also a sample of paper is waterproofed by immersion in a10% solution of vinyl trifiuoromethyl sulfide polymer inphenyltrifluoromethylthioacetylene at about followed by drying in avacuum oven.

Since obvious modifications and equivalents in the invention will beevident to those skilled in the chemical arts, we propose to be boundsolely by the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A fluoroalkylthioacetylene of the formula R SCECR wherein R is apolyfluoroalkyl group of up to 10 carbons and R is selected from thegroup consisting of hydrogen, monovalent hydrocarbon of up to 10carbons, R 3, and R;.

2. Phenyl(trifiuoromethylthio)acetylene.

3. Bis(trifiuoromethylthio)acetylene.

4. Trifluoromethylthiopentafiuoroethylthioacetylene.

5. Phenyl(chlorodifluoromethylthio)acetylene.

6. The process which comprises reacting a polyfluoroalkanesulfenylhalide with a compound of the formula XC CY, wherein Y is selected fromthe group consisting of the alkali metals and halomagnesium, and X isselected from the group consisting of hydrogen, monovalent hydrocarbonof up to 10 carbons, polyfluoroalkyl of up to 10 carbons and Y.

7. The process which comprises reacting a phenyl- 7 8 ethynylmagnesiumhalide with a trifluorometh-anesulfenyl 11. The process which comprisesreacting ethynylenedihalide. magnesium bromide withtrifluoromethanesulfenyl ch10- 8. The process which comprises reactingphenylethynylride. magnesium bromide with trifiuoromethanesulfenyl chlo-12. The process Which comprises reacting a phenylid 5 ethynylmagnesiumhalide with a chlorodifluoromethane- 9. The process which comprisesreacting lithium phen- Sulffinyl halideylacetylide withtrifluoromethanesulfenyl chloride. The Process Whlch Comprises reactingP ethynylmagnesiurn bromide with chlorodifiuoromethane- 10. The processwhich comprises reacting an ethynylsulfenyl chloride.

enedimagnesium halide with a trifluoromethanesulfen vl halide. w Noreferences cited.

1. A FLUOROALKYLTHIOACETYLENE OF THE FORMULA RFSC$CR WHEREIN RF IS APOLYFLUOROALKYL GROUP OF UP TO 10 CARBONS AND R IS SELECTED FROM THEGROUP CONSISTING OF HYDROGEN, MONOVALENT HYDROCARBON OF UP TO 10CARBONS, RFS, AND RF.
 6. THE PROCESS WHICH COMPRISES REACTING APOLYFLUOROALKANESUFENYL HALIDE WITH A COMPOUND OF THE FORMULA XC$CY,WHEREIN Y IS SELECTED FROM THE GROUP CONSISTING OF THE ALKALI METALS ANDHALOMAGNESIUM, AND X IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN,MONOVALENT HYDROCARBON OF UP TO 10 CARBONS, POLYFLUOROALKYL OF UP TO 10CARBONS AND Y.